This invention pertains to a method of rendering paper and textile fabric substrates water repellent by contacting them with water-dispersible aqueous emulsions of epoxy-silicones and in particular to the use of anionic sulfonate emulsifiers.
Aqueous emulsions of epoxy-silicones have been used for sizing paper and textile fabrics using non-ionic emulsifiers to prepare the water-dispersible emulsions. These previously known techniques however invariably require the use of a catalyst to obtain reasonable cure times. In the case of commercial paper board, where the presence of catalysts are undesirable, cure times of seven to ten days are required before acceptable water repellency is imparted to the paper board. Commercial grades of filter paper treated by using non-ionic emulsions of epoxy-silicones require elevated temperatures to effect cure.
Catalysts, such as, metal salts and polymer anhydrides will accelerate the rate of cure of the substrates but their use adds to water pollution problems, productions costs and also results in a short bath life for the water-dispersible emulsions of epoxy-silicones.
It is therefore an object of this invention to provide a method for imparting water repellency to paper and textile fabric substrates with water dispersible emulsions of epoxy-silicones with shorter cure times without the addition of curing catalysts.